scholarly journals Preparation and Properties of 3D Chitosan Microtubes

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Natalia O. Gegel ◽  
Anna B. Shipovskaya ◽  
Luba S. Vdovykh ◽  
Tatiana S. Babicheva
Keyword(s):  
Mechanism Of Formation ◽  
Vascular Prostheses ◽  
Elongation At Break ◽  
High Adhesion ◽  
Deformation Properties ◽  
Polymeric Layer ◽  
High Proliferative Activity ◽  
Lactic Acids ◽  
Cellular Culture

The preparation of 3D chitosan microtubes from polymer solutions in citric and lactic acids by the wet and dry molding methods is described. The mechanism of formation of the insoluble polymeric layer constructing the walls of these microtubes is characterized. The microtubes obtained from chitosan solutions in citric acid are found to have a fragile porous inner layer. For those obtained from chitosan solutions in lactic acid the morphology, elastic-deformation properties, physicomechanical properties, and biocompatibility were assessed. These samples have smooth outer and inner surfaces with no visible defects and high values of elongation at break. The strength of the microtubes obtained by the dry method is much higher than in the case of the wet one. A high adhesion and high proliferative activity of the epithelial-like MA-104 cellular culture on the surface of our microtubular substrates in model in vitro experiments were revealed. Prospects of using chitosan microtubes as vascular prostheses are suggested.

An in vitro rotation model composed of disposables for investigation of endothelialization of artificial vascular prostheses

2012 ◽  
Vol 60 (S 01) ◽  
Author(s):  
M Lescan ◽  
J Kobba ◽  
M Avci-Adali ◽  
B Neumann ◽  
N Perle ◽  
...  
Keyword(s):  
Vascular Prostheses ◽  
Rotation Model

Binding of Tissue Plasminogen Activator to Vascular Grafts

1989 ◽  
Vol 61 (01) ◽  
pp. 131-136 ◽  
Author(s):  
Richard A Harvey ◽  
Hugh C Kim ◽  
Jonathan Pincus ◽  
Stanley Z Trooskin ◽  
Josiah N Wilcox ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Fibrinolytic Activity ◽  
Polymer Surface ◽  
Enzymic Activity ◽  
Vascular Prostheses ◽  
Chemically Modified ◽  
Insoluble Surfactant ◽  
Tissue Plasminogen

SummaryTissue plasminogen activator labeled with radioactive iodine (125I-tPA) was immobilized on vascular prostheses chemically modified with a thin coating of water-insoluble surfactant, tridodecylmethylammonium chloride (TDM AC). Surfactant- treated Dacron, polytetrafluoroethylene (PTFE), silastic, polyethylene and polyurethane bound appreciable amounts of 125I- tPA (5-30 μg 125I-tPA/cm2). Upon exposure to human plasma, the amount of 125I-tPA bound to the surface shows an initial drop during the first hour of incubation, followed by a slower, roughly exponential release with a t½ of appoximately 75 hours. Prostheses containing bound tPA show fibrinolytic activity as measured both by lysis of clots formed in vitro, and by hydrolysis of a synthetic polypeptide substrate. Prior to incubation in plasma, tPA bound to a polymer surface has an enzymic activity similar, if not identical to that of the native enzyme in buffered solution. However, exposure to plasma causes a decrease in the fibrinolytic activity of both bound tPA and enzyme released from the surface of the polymer. These data demonstrate that surfactant-treated prostheses can bind tPA, and that these chemically modified devices can act as a slow-release drug delivery system with the potential for reducing prosthesis-induced thromboembolism.

scholarly journals Ultra-strong bio-glue from genetically engineered polypeptides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chao Ma ◽  
Jing Sun ◽  
Bo Li ◽  
Yang Feng ◽  
Yao Sun ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Covalent Bond ◽  
Genetically Engineered ◽  
Supramolecular Interactions ◽  
Molar Ratio ◽  
High Adhesion ◽  
Strong Adhesion ◽  
Order Of Magnitude

AbstractThe development of biomedical glues is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, i.e. strong adhesion and adaption to remodeling processes in healing tissue. Here, we report a biocompatible and biodegradable protein-based adhesive with high adhesion strengths. The maximum strength reaches 16.5 ± 2.2 MPa on hard substrates, which is comparable to that of commercial cyanoacrylate superglue and higher than other protein-based adhesives by at least one order of magnitude. Moreover, the strong adhesion on soft tissues qualifies the adhesive as biomedical glue outperforming some commercial products. Robust mechanical properties are realized without covalent bond formation during the adhesion process. A complex consisting of cationic supercharged polypeptides and anionic aromatic surfactants with lysine to surfactant molar ratio of 1:0.9 is driven by multiple supramolecular interactions enabling such strong adhesion. We demonstrate the glue’s robust performance in vitro and in vivo for cosmetic and hemostasis applications and accelerated wound healing by comparison to surgical wound closures.

scholarly journals The Influence of a Knitted Hydrophilic Prosthesis of Blood Vessels on the Activation of Coagulation System—In Vitro Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1600
Author(s):  
Maria Szymonowicz ◽  
Maciej Dobrzynski ◽  
Sara Targonska ◽  
Agnieszka Rusak ◽  
Zbigniew Rybak ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Initial Period ◽  
In Vitro Study ◽  
Vascular Prosthesis ◽  
Coagulation System ◽  
Factor Xii ◽  
Scanning Calorimetry ◽  
Vascular Prostheses ◽  
Control Value

The replacement of affected blood vessels of the polymer material can cause imbalances in the blood haemostatic system. Changes in blood after the implantation of vascular grafts depend not only on the chemical composition but also on the degree of surface wettability. The Dallon® H unsealed hydrophilic knitted vascular prosthesis double velour was assessed at work and compare with hydrophobic vascular prosthesis Dallon®. Spectrophotometric studies were performed in the infrared and differential scanning calorimetry, which confirmed the effectiveness of the process of modifying vascular prostheses. Determination of the parameters of coagulation time of blood after contact in vitro with Dallon® H vascular prosthesis was also carried out. Prolongation of activated thromboplastin time, decreased activity of factor XII, IX and VIII, were observed. The prolonged thrombin and fibrinogen were reduced in the initial period of the experiment. The activity of plasminogen and antithrombin III and protein C were at the level of control value. The observed changes in the values of determined parameters blood coagulation do not exceed the range of referential values for those indexes. The observed changes are the result of considerable blood absorptiveness by the prosthesis of blood vessels and their sealing.

Attenuation of Flow Disturbances in Tapered Arterial Grafts

1989 ◽  
Vol 111 (4) ◽  
pp. 303-310 ◽  
Author(s):  
R. A. Black ◽  
T. V. How
Keyword(s):  
Pulsatile Flow ◽  
Reynolds Numbers ◽  
Axial Distance ◽  
Pulsed Ultrasound ◽  
Arterial Grafts ◽  
Vascular Prostheses ◽  
Disturbance Intensity ◽  
Flow Disturbances ◽  
Percent Area

Flow disturbances in tapered arterial grafts of angles of taper between 0.5 and 1.0 deg were measured in vitro using a pulsed ultrasound Doppler velocimeter. The increase in transition Reynolds numbers with angle of taper and axial distance was determined for steady flow. The instantaneous centerline velocities were measured distal to a 50 percent area stenosis (as a model of a proximal anastomosis), in steady and pulsatile flow, from which the disturbance intensities were calculated. A significant reduction in post-stenotic disturbance intensity was recorded in the tapered grafts, relative to a conventional cylindrical graft. In pulsatile flow with a large backflow component, however, there was an increase in disturbance intensity due to diverging flow during flow reversal. This was observed only in the 1.0 deg tapered graft. These findings indicate that taper is an important consideration in the design of vascular prostheses.

In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens

1991 ◽  
Vol 54 (7) ◽  
pp. 496-501 ◽  
Author(s):  
ARTHUR HINTON ◽  
GEORGE E. SPATES ◽  
DONALD E. CORRIER ◽  
MICHAEL E. HUME ◽  
JOHN R. DELOACH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Mixed Cultures ◽  
Enterococcus Durans ◽  
E Coli ◽  
Pure Cultures ◽  
In Vitro Inhibition ◽  
Lactic Acids

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella.

The Effect of Silane on the Biomechanical Properties of PEEK/HA Composite

2015 ◽  
Vol 1125 ◽  
pp. 426-431
Author(s):  
Ahmad Ramli Rashidi ◽  
Mat Uzir Wahit ◽  
M.R. Abdullah ◽  
Mohammed Rafiq Abdul Kadir
Keyword(s):  
Cell Proliferation ◽  
Coupling Agent ◽  
U937 Cell ◽  
Biomechanical Properties ◽  
Screw Extruder ◽  
Elongation At Break ◽  
Single Screw ◽  
Single Screw Extruder ◽  
Bioactive Composites

Bioactive composites containing Polyetheretherketone / Hydroxyapatite (PEEK/HA) were prepared using nanomixer single screw extruder and injection molding. The loading of HA in PEEK matrix was made at different concentrations ranging from 10 wt% to 30 wt%. HA was treated with (3-Aminopropyl) trimethoxysilane, coupling agent, and compared to untreated HA in PEEK/HA composite to evaluate the changes in the biomechanical properties and cytotoxicity. The biomechanical properties including elongation at break and impact properties were assessed. Cell proliferation test was also performed with U937 cell line in the silane treated and untreated PEEK/HA composite. The results showed that silane coupled PEEK-HA had in general improved biomechanical properties than untreated HA and did not show cytotoxicity in vitro.

A multifunctional poly(acrylic acid)/gelatin hydrogel

2009 ◽  
Vol 24 (5) ◽  
pp. 1653-1661 ◽  
Author(s):  
Qunwei Tang ◽  
Jihuai Wu ◽  
Jianming Lin ◽  
Shijun Fan ◽  
De Hu
Keyword(s):  
Acrylic Acid ◽  
Transport Model ◽  
Interpenetrating Network ◽  
Hybrid Hydrogel ◽  
Elongation At Break ◽  
Gelatin Hydrogel ◽  
Preparation Conditions ◽  
Aqueous Solution Polymerization ◽  
Poly Acrylic Acid

A poly(acrylic acid)/gelatin interpenetrating network hydrogel was synthesized by aqueous solution polymerization. The influences of preparation conditions including cross-linker, initiator, gelatin content, and neutralization degree on the swelling ratios of the hydrogels are investigated. The swelling, mechanical strength, biodegradability, and drug-release properties of poly(acrylic acid)/gelatin hydrogel are evaluated. The hydrogel has excellent mechanical properties; tensile strength is 1500 kPa, and elongation at break is 887%, respectively. The in vitro biodegradation shows that an interpenetrating network structure exists in the poly(acrylic acid)/gelatin hybrid hydrogel. A release study indicates that the theophylline release from the hydrogel depends on the cross-linking density of the hydrogel and pH of the medium, and the drug diffusion obeys an anomalous transport model.

Relationship between intake of silage and its chemical composition and in vitro digestibility

1972 ◽  
Vol 23 (1) ◽  
pp. 25 ◽  
Author(s):  
DC Brown ◽  
JC Radcliffe
Keyword(s):  
Dry Matter ◽  
In Vitro Digestion ◽  
Ammonia Nitrogen ◽  
Matter Content ◽  
In Vitro Digestibility ◽  
Dry Matter Content ◽  
Regression Analyses ◽  
Lactic Acids

Twenty experimental silages were made from seven pasture species at different stages of maturity. In vivo dry matter, organic matter, and energy ad libitum intakes and digestibilities of the silages were determined with standardized pairs of Merino wethers. The following chemical characteristics of the silages were measured: nitrogen, ammonia nitrogen, total titratable acids, acetic, propionic, butyric, and lactic acids, total volatiles lost during oven drying, lactic acid as a percentage of the total organic acids, pH, acid pepsin dry matter disappearance, dry matter content, and in vitro digestibility and rate of digestion. When all 20 silages were considered, energy intakes on a body weight basis were significantly related to silage pH (r = 0.55) and rate of in vitro digestion (r = 0.58). When the five legume silages were removed from the analysis and only the 15 grass-dominant silages were considered, dry matter intakes were significantly related to acetic (r = –0.57) and propionic acid (r = –0.55) concentrations. Multiple regression analyses did not significantly increase the accuracy of predicting intake. The results suggested that silage intake was negatively related to the degree of fermentation that occurred during the ensiling process.

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